Messages in this thread | | | Date | Mon, 9 Jun 2008 17:09:29 +0200 | From | "Vegard Nossum" <> | Subject | Re: [bug, 2.6.26-rc4/rc5] sporadic bootup crashes in blk_lookup_devt()/prepare_namespace() |
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On 6/9/08, Cornelia Huck <cornelia.huck@de.ibm.com> wrote: > On Mon, 9 Jun 2008 16:28:09 +0200, > > "Vegard Nossum" <vegard.nossum@gmail.com> wrote: > > Everywhere else where we traverse the struct class->devices list, they > > have down(&class->sem); first and up(&class->sem); afterwards. > > > > Commit fd04897bb20be29d60f7e426a053545aebeaa61a even has this hunk: > > @@ -177,8 +177,7 @@ struct class { > > struct list_head devices; > > struct list_head interfaces; > > struct kset class_dirs; > > - struct semaphore sem; /* locks both the children and interface > > - > > + struct semaphore sem; /* locks children, devices, interfaces */ > > struct class_attribute * class_attrs; > > struct class_device_attribute * class_dev_attrs; > > struct device_attribute * dev_attrs; > > > > > > So why doesn't block/genhd.c do this too? It seems to me that the > > mutex locking here is simply a remnant of old code that happened to > > not crash in most cases by chance. > > > > > Does this crash happen with the conversion to the class iterator > functions (should be in linux-next) as well? They take the class > mutex...
Ah, you mean this:
commit bb7ee70edb8745021c17ab604f2f4c897004e1c5 Author: Greg Kroah-Hartman <gregkh@suse.de> Date: Thu May 22 17:21:08 2008 -0400
block: make blk_lookup_devt use the class iterator function
Use the proper class iterator function instead of mucking around in the internals of the class structures.
Cc: Kay Sievers <kay.sievers@vrfy.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
So it should already be fixed, then. But I guess we'll have to wait for Ingo to run another couple of thousand tests to know the answer ;-)
Thanks!
Hm. Bugs already fixed elsewhere seems to be a recurring theme... I'll look harder for changes/fixes in other trees the next time :-(
Vegard
PS: But what about printk_all_partitions()? There are more than just this instance of the device list traversal code that don't use the class semaphore.
PPS: Was that patch ever posted to LKML? I couldn't seem to find it.
-- "The animistic metaphor of the bug that maliciously sneaked in while the programmer was not looking is intellectually dishonest as it disguises that the error is the programmer's own creation." -- E. W. Dijkstra, EWD1036
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